Send all-window-drawn message of caller directly

It was posting to display thread and then ui thread, so if
display thread is busy, the screen on callback can be delayed.

So just let caller specify the message to send, then the callback
can run on the target thread directly. It also eliminates the concern
of arbitrary runnable which may be dangerous to run inside WM lock.

Also move the end of trace waitForAllWindowsDrawn to where
finishWindowsDrawn is called so it is more precise.

Bug: 288581490
Test: Turn on screen and observe the end of trace
      waitForAllWindowsDrawn won't be affect by the messages
      in display thread.
Change-Id: I875d3bec8a93a83798c093cd3c099fe8c022ae4b